Influence of axial spacing on hydraulic performance of tubular turbine
YANG Sunsheng1, FANG Tian1, PUNIT Singh2, ZHOU Cheng1, ZHAO Erce1, WANG Tao3
1. National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China; 2. Centre for Sustainable Technologies, Indian Institute of Science, Bangalore, Karnataka 560012, India; 3. Key Laboratory of Fluid and Power Machinery, Ministry of Education, Xihua University, Chengdu, Sichuan 610039, China
Abstract：In order to find a reasonable value for the axial distance between the guide vane and the runner in the tubular turbine, as well as obtaining good hydraulic performance while ensuring its compact structure, the numerical calculation of the full flow field was carried out for the microtubular turbine models with axial distance s of 30, 40, 50, 60 and 70 mm between the guide vane and the runner to study the influence of axial spacing on the hydraulic performance of a tubular turbine by combining numerical calculation and experiments. The results show that: the water head of the turbine increases with the expansion of the axial distance, and the axial (shaft) power of the hydraulic turbine increases first and then stabilizes with the expansion of the axial distance. Considering various flow conditions, higher efficiency was obtained, and the efficiency of the model reaches the maximum when s=40 mm. Choosing appropriate axial spacing can improve the pressure distribution and flow pattern on the surface of runner blades. Excessive axial spacing will cause negative impact at the inlet of the runner and result in flow separation. The turbulent kinetic energy at the outlet of the runner decreases with the increase of axial spacing. under optimal working conditions, when the axial distance is spacing is expanded from 30 mm to 70 mm, the hydraulic loss inside the runner gradually increases by 15.6%, while the hydraulic loss in the outlet pipe decreases by 19.7%, and the total hydraulic loss shows an increasing trend. Considering comprehensively, s=40 mm was selected as the final scheme.
